In both terrain and cities, a traditional map can be used for navigation. In other words, a location marked on the map is sought with the aid of the terrain. However, navigation based on a map and fixed points in the environment requires skill. Nowadays, it is also possible to use a mobile device for navigation. However, a mobile device is expensive and requires a functioning data network.
Particularly when navigating over short distances, along which there are many people, both the accuracy and the usability of the aforementioned appliances are insufficient. The accuracy of a map is poor and fixed points are difficult to distinguish among a crowd of people. In a crowd, it is difficult to use mobile devices and, as stated above, their accuracy is even poorer than that of a map. Uncertain navigation is made even more difficult by a possibly tight timetable, as well as uncertainty as to the location of the end point.